Acoustic studio led screen

ABSTRACT

Light-emitting or light-reflecting displays with enhanced visual and acoustic characteristics, include a display based on light-emitting elements such as light-emitting diodes (LEDs). A LED display or screen with enhanced acoustic characteristics and/or improved visual performance is herewith presented for particular use or application in a studio environment where the quality performance of both image and sound, when being captured by a camera or an audience, is challenged. The use and applications of such display, include systems and methods making use of such display, and more particularly concerning the use and application of such displays in studio environments.

TECHNICAL FIELD

The invention relates to a display with enhanced visual and/or acousticcharacteristics, more in particular the invention relates to the lightsource display being based on light-emitting elements such as forexample light-emitting diodes (LEDs). A LED display or screen withenhanced acoustic characteristics is herewith presented. The inventionalso relates to the use and applications of such LED display, includingsystems and methods making use of such LED display.

BACKGROUND OF THE INVENTION

Existing displays, both using light emitting (e.g. LED or OLED) orreflective technologies (e.g. LCD) that are used for studioapplications, meaning within for example a broadcasting environment, ingeneral show defects on the final screen that is seen by the public oruser. Complex and cumbersome manipulation is then often performed tomake images acceptable again for the viewer. Only a mere acceptabilityis provided by lack of better availability. A robust and simple solutionis not provided in the art.

Moreover, in a recording studio, next to the use of displays such as LEDdisplays, audio from all kind of sources from any possible locationneeds to be taken into account. Cameras are used for recording in thestudio. In addition to the images from the displays, the structural andfurniture environment of the studio, the actors or people presenttherein, as well as the audio being produced, are captured by thecameras and/or microphones for recording, and in case of a recordingevent open for the public, these are also captured by the audience.Hence, a high-quality representation of both visual and acousticperformance is quite a challenge in this respect. In other words, thereis a need for a studio display with enhanced acoustic characteristicsand adapted high-quality visual features for the particular purpose ofstudio applications.

AIM OF THE INVENTION

The aim of the invention is to cover display devices, such as forexample light-emitting display devices, which are optimized forstudio/on screen/camera applications, i.e. for example a studio having aLED screen (e.g. in the back, behind actors or presenters or stage) andusing a camera for recording scenes. The light-emitting display devicesare e.g. based on LED technology, but not limited thereto, and hencealso including other possible comparable light-emitting sources as knownin the art. Further on, this invention can also be used for displaysbased upon reflective light technologies (e.g. LCD displays withoutbacklight), bi-stable reflective displays or interferometric basedreflective displays. Both picture performance adaptations as well asacoustic performance enhancement are considered to aim for a goodquality recording on camera of a studio event.

SUMMARY OF THE INVENTION

The invention relates to methods (and related circuits and set-up's) forimproving a display's visual and/or acoustic performance in relation toa camera recording the image displayed by the display, wherein thedisplay comprises a plurality of distinct light sources more inparticular one of said distinct sources being Light Emitting Diode(LED), and/or in relation to audio recording wherein the display needsspecial precautions for reducing environmental noise and undesiredreflections. Instead of a display based on distinct light sources,another type of display based on reflective light areas (such as LCD forinstance) can also be used. It is noted that within this text mainly alight-emitting display, and a LED display in particular will be referredto, although it is herewith understood that the invention regardingvisual and acoustic performance enhancement of a display, also appliesfor displays based on reflective technologies.

The invention especially relates to displays wherein the light sourcesare driven by (bit size limited) (PWM) drivers with a set fixed current.

One or more of the proposed methods in accordance with the invention,analyse the output of the display required for displaying a (reference)image sequence and derive setting (like a set fixed current) therefromand control said light source(s) accordingly.

The invention also relates to optimized exploiting the (full or widerthan standard) dynamic range of a light source display by properlysetting said fixed current.

The invention relates to improving a light source display's visualperformance, wherein one adapts the light source input signal to the bitsize limited PWM drivers, to compensate for various effects such asnonlinearities caused by setting the current as indicated above and/ornonlinearities, caused by the (RLC) behaviour of the board whereon saidlight sources are mounted and/or due to temperature effects.

One or more of the proposed methods relate to achieve the ideal humaneye transfer function, preferably by using control features (like theclock) of said PWM drivers. By using this control feature, the bit sizelimit reduces drastically.

The invention relates to displays in a studio environment, meaningarrangements of one or more displays, one or more cameras at least inpart recording what is displayed on one or more of these displays, andmore in particular such arrangements also include typically soundinfrastructure like sound generating and/or sound capturing instruments(like microphones).

In relation to such studio environments and sound includingarrangements, it is worth emphasizing that the display may be (andtypically is) also an (unwanted) sound generating instrument,particularly the display subsystems like coolers and/or power supplythereof. Moreover, the display can also reflect sound that it hascaptured from the environment. Especially in a closed environment andwhen using a curved display, audio signals can be strongly reflectedback into the studio, herewith disturbing the actors, the audienceand/or the sound being captured by a microphone.

It is an aspect of the invention to provide measures to improve (besidesthe visual performance also) the sound performance in such studioenvironment by providing related adaptations to said displays, forexample by means of removing or turning off components within thedisplay making a lot of noise or sound, but also for example by means ofproviding sound absorbing material, or decreasing the display's soundreflecting characteristics by means of adapting the display or LEDscreen towards a more open structure.

In a further embodiment thereof, also the driving of the display isadapted to minimize bad sound performance of the studio.

As an exemplary embodiment thereof, as indicated elsewhere in thedescription, the visual performance is influenced (heavily) bytemperature effects on the light sources (LEDs) of the display. While inordinary displays one will combat this by providing sufficient coolingfacilities, in the invention instead, realizing the negative effect onsound performance, temperature compensation in the control of thedisplay is included, thereby leaving room for lower cooling demand (andhence lower unwanted sound generation).

In a further embodiment thereof, it is realized that the power supplybehaviour and/or display driver behaviour and/or display behaviouritself in relation to heat production depends also heavily on the waythe display is driven or controlled. As an exemplary embodiment thereof,as indicated elsewhere in the description, the control is based onanalysing a reference sequence to thereby find a tuned (just enough)control approach, which influences positively the settings (like currentsetting) of the driver circuitry (and the related power supply) and alsothe light throughput of the display itself, in relation to heatproduction, thereby also lowering cooling demands, with the effects onsound as indicated already above.

In a first aspect of the invention, a method is provided wherein one ormore displays (e.g. LED displays) are part of a studio environment,further comprising one or more cameras at least in part recording whatis displayed on one or more of these displays. The studio environmentmay further include sound infrastructure. According to an embodiment,the displays are adapted to minimize their sound generating behaviour,and/or are adapted to maintain good visual performance irrespective toan improved sound generating behaviour. According to an embodiment, thedisplays are adapted to optimize sound behaviour of the studio, inparticular either said displays are provided with acoustic absorbingmaterial and/or adapted to let part of the sounds through in order toavoid acoustic reflections.

In a second aspect of the invention, a method is provided for improvingthe interplay of a light source display with a camera recording theimage displayed by the light source display, the method comprising: (i)receive the light source input signal; and (ii) apply the light sourceinput signal to said light source, after a programmable delay (relativeto a synchronisation signal related to said camera). According to anembodiment the type of light source used for the display is a LightEmitting Diode (LED) and/or said programmable delay is selected toimprove said interplay of said light source display with said camera,more in particular to reduce banding effects when recording on camera.The cause of the banding effect is due to different timing when thecamera shutter opens compared to the discrete PWM generation for thelight sources.

In a third aspect of the invention, a method is provided for optimizedexploiting the (wider than standard) dynamic range of a light sourcedisplay comprising a plurality of distinct light sources with bit sizelimited drivers, the method comprising: for at least one light source ofsaid display, (i) determining the dynamic range required for displayinga (reference) image sequence; (ii) set a reference or off-set value(e.g. current) of the driver of said corresponding light source in themiddle of said required dynamic range; (iii) (equally) discretize therequired dynamic range around said set reference or off-set value basedon the (available) bit size of said driver; and (iv) control said lightsource accordingly. With the term ‘wider than standard’ is meant thatwhen using a bit size limited driver, the aim is to try to use more bitsthan is or would be the case for standard in the art displays. Accordingto an embodiment, the type of light source used for the display is aLight Emitting Diode (LED), and/or the light sources are driven by PWMdrivers with a set fixed current, being said set reference or off-setvalue.

According to an aspect of the invention, a method is provided forimproving a light source display visual performance for a light sourcedisplay, comprising a plurality of distinct light sources, mounted on a(PCB) board, the method comprising: for at least one light source, (i)receive the light source input signal; (ii)) adapt the light sourceinput signal, to compensate for nonlinearities, caused by the nonlinearbehaviour between the change of said reference or off-set value and thelight output of said light source perceived by the human eye (preferablyafter camera recording the image displayed by the light source display);(iii) apply the adapted light source input signal to said light source.

According to an aspect of the invention, a method is provided foroptimized exploiting the (wider than standard) dynamic range (towards anoptimized maximum) of a light source display comprising a plurality ofdistinct light sources with bit size limited drivers, the methodcomprising: for the plurality of light sources of said display connectedto the same driver, (i) for each of them, determining the dynamic rangerequired for displaying a (reference) image sequence; (ii) set areference or off-set value of the driver of said corresponding lightsource in the middle of the maximum of said required dynamic ranges;(iii) for each of them discretize the required dynamic range around said(common) set reference or off-set value based on the (available) bitsize of said driver; and (iv) control said light sources accordingly.The term optimized maximum is further explained. The higher the lightoutput in high-dynamic range images, the more bit depth there is neededto retain sufficient detail in the low lights. Aiming for an optimizedmaximum in dynamic range means for example that for as high as possiblelight output, as most as possible bit depth is aimed at, and this beingmore than would be the case for standard state-of-the-art LED screens.The light source used for instance can be a Light Emitting Diode (LED),and/or the light sources are possibly driven by PWM drivers with a setfixed current, being said reference or off-set value.

According to further aspect of the invention, a method is provided forcontrolling a light source display comprising a plurality of distinctlight sources, wherein the light sources are driven by PWM drivers witha set fixed current, wherein the human eye transfer function (relatinglight output of the light source to the light perceived by the humaneye, preferably after camera recording or both taking into account aftercamera recording and direct perception) adaptation, being realized (atleast in part) by modulating the clock of said PWM drivers, inparticular use of high frequency for low light and low frequency forhigh light outputs. The method may further include compensation for(RLC) nonlinearities of the (PCB) board, and/or nonlinearities caused bychange of reference or off-set value of said drivers.

According to further aspect of the invention, a method is provided foroptimized exploiting the (wider than standard) dynamic range of a lightsource display comprising a plurality of distinct light sources with bitsize limited drivers, the method comprising: for each light pixel, foreach colour therein and related light source of said display, (i)determining the dynamic range required for displaying a (reference)image sequence; (ii) set a reference or off-set value of the driver ofsaid corresponding light source in the middle of said required dynamicrange; (iii) (equally) discretize the required dynamic range around saidset reference or off-set value based on the (available) bit size of saiddriver; and (iv) control said light source accordingly.

In an aspect of the invention, a method is provided for improving alight source display visual performance for a light source display,comprising a plurality of distinct light sources, mounted on a (PCB)board, the method comprising: for at least one light source, (i) receivethe light source input signal; (ii)) adapt the light source inputsignal, to compensate for nonlinearities, caused by the (RLC) behaviourof said board; and (iii) apply the adapted light source input signal tosaid light source. The light source can be a Light Emitting Diode (LED).According to an embodiment, said visual performance is the visualperformance perceived by a human eye before or after camera recordingthe image displayed by the light source display.

According to an embodiment, said adaptation being part of or based onthe human eye transfer function (relating light output of the lightsource to the light perceived by the human eye) preferably after camerarecording or both taking into account after camera recording and directperception.

According to an embodiment, for one or more (particular a few, typicallylow light wherein nonlinearities cause most detrimental visualperformance effects such as for example not displaying desired colour ornot all light sources lighting up equally when it is desired) lightoutput points (in said human eye transfer function) a correction factoris determined, and for all other points a non-continuous interpolation(e.g. by use of a spline function) is performed. The method can be usedon a per light source basis or alternatively for a set of light sourceslocated nearly on said (PCB) board in a region.

According to an aspect of the invention, a method is provided fordetermining adaptation information (correction factors) suited for usein one of the methods as above, the method comprising: (a) displaying animage or sequence of images (video) with said light source display; (b)determine the visual performance perceived by a human eye (and/or aftercamera recording the image displayed by the light source display); (c)compare this visual performance with the ideal visual performance; (d)compute said adaptation information (correction factors) based on saidcomparison. The method can be applied to high density resolutiondisplays (0.625 mm pixel pitch and up). The method can also be appliedto displays wherein the light sources are driven by PWM drivers with aset fixed current.

In a further aspect of the invention, a method is provided for improvinga light source display visual performance for a light source display,comprising a plurality of distinct light sources, wherein said visualperformance is the visual performance perceived by a human eye bothbefore or after camera recording the image displayed by the light sourcedisplay, the method comprising: providing a light source display with atleast 4 different colours (which may be a partly overlapping spectrum);and for at least one light source, (i) receive the light source inputsignal; (ii) adapt the light source input signal, to compensate forcamera conversion effects; (iv) further adapt the light source input tocompensate for the visual performance perceived by a human eye directlyafter said camera conversion effect compensation and (iv) apply theadapted light source input signal to said light source. According to anembodiment, the light source being a Light Emitting Diode (LED), and/orsaid colours consisting of RED, GREEN, BLUE and CYAN and/or ORANGE,and/or said colours consisting of RED, GREEN, BLUE and WHITE.

In a further aspect of the invention, a method is provided for improvinga light source display visual performance for a light source display themethod comprising: for each light pixel (a pixel having at least 2colours), for each colour therein (i) determining the maximum requiredlight output required for displaying a (reference) image sequence; (ii)set a reference or off-set value of the driver of said correspondinglight source accordingly (same maximum); and (iii) control said lightsource accordingly. According to an embodiment, said light source beinga Light Emitting Diode (LED). The method can be applied to displayswherein the light sources are driven by PWM drivers with a set fixedcurrent, being said reference or off-set value. According to anembodiment, said determining the maximum required light output requiredtakes into account the camera recording of the image displayed by saiddisplay.

In a further aspect of the invention, a method is provided for improvinga light source display visual performance for a light source display,comprising a plurality of distinct light sources, mounted on a (PCB)board, the method comprising: for at least one light source, (i) receivethe light source input signal; (ii) adapt the light source input signal,to compensate for temperature effects; and (iii) apply the adapted lightsource input signal to said light source. According to an embodiment,said temperature effect is determined by monitoring the on time of saidlight source and estimating said temperature effect therefrom. The lightsource display may further comprise temperature sensors; and saidtemperature sensor can be used for calibrating said estimation.Moreover, said temperature sensor can be used also for said adaptation,by e.g. using a behavioural temperature model of the light sourcedisplay. Means for monitoring on-time (e.g. digital counters) can alsobe provided and can improve above accuracy of temperature compensationby e.g. also using on-time of neighbouring light sources.

According to an aspect of the invention, a method is provided fordetermining the relation between the on time of a light source, mountedon a (PCB) board and the temperature effect therefrom.

According to another aspect of the invention, a method is provided fordetermining the relation between the temperature as measured by atemperature sensor mounted on a board and the temperature at a lightsource at a certain distant at said board.

In an aspect of the invention, one of the methods above are provided fordisplays being part of a studio environment, with one or more displays,one or more cameras at least in part recording what is displayed on oneor more of these displays. According to an embodiment, said studioenvironment further includes sound infrastructure, and/or said displaysare adapted to minimize their sound generating behaviour. According toan embodiment, said displays are adapted to maintain good visualperformance irrespective to the improved sound generating behaviour.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates prior-art solution in compensating forthe frame delay of the video display system, by means of having thebackground played out a few frames earlier compared to the front action.

FIG. 2 shows an embodiment for illustrating the aspect of vertical syncupdate in relation to camera shutter-time, in accordance with theinvention.

FIG. 3 shows an embodiment for illustrating the aspect of currentsetting for the individual colours (instead of PWM tuning) for achievingrequired colour spectrum, in accordance with the invention.

FIG. 4 illustrates RLC behaviour and non-linear effects, and shows anembodiment for illustrating how to compensate for non-linear effects orso-called non-linearities using spline functions or more generalnon-discontinuous interpolation, in accordance with the invention.

FIG. 5 graphically illustrates gamma correction with a spline function,in accordance with the invention.

FIGS. 6A and 6B show examples of an open screen.

FIG. 7 shows an example of acoustic absorbing material provided inbetween light-emitting elements.

FIG. 8 shows examples of acoustic surfaces in accordance with theinvention.

FIG. 9 shows an example of acoustic absorbing structures provided inbetween LEDs of a LED board, in accordance with the invention.

FIG. 10 shows an example of a standard screen and its sound reflectionsin comparison with an acoustic enhanced screen, in accordance with theinvention.

FIG. 11 shows an embodiment of a studio setting, wherein a camera issurveying a display wall making noise, in accordance with the invention.

FIG. 12 shows an embodiment of a studio setting, wherein a camera issurveying an actor and a display wall of which the noise is suppressedor reduced by means of for example fan regulation or light outputadaptation, in accordance with the invention.

FIG. 13 shows an embodiment of a studio setting, wherein a camera issurveying actors talking and a display wall of which the noise issuppressed or reduced as FIG. 12, and wherein the display wall isprovided with acoustic absorbing or diffusing material, or the displaywall having an open structure, such that audio wave reflections from thesurface of the display wall are suppressed or reduced, in accordancewith the invention.

FIG. 14 schematically illustrates the light emitted colour spectrum forRed, Green, Blue of the display and of the camera respectively,including additional colours to be added (e.g. cyan, orange) to thedisplay, such that the human eye visual perception of all colours iscorrect.

FIGS. 15A and 15B illustrate a schematic overview of a spectral analysissystem for matching the spectrum of a multi-spectral display (withmulti-colour LEDs) to the spectrum of any white light source whilst alsotaking into account the camera sensitivities, in accordance with theinvention.

FIG. 16 is the corresponding flow diagram of FIGS. 15A and 15B.

FIG. 17 shows the PQ gamma curve as defined in BT2100.

FIG. 18 shows an embodiment for illustrating the aspect of grey scaleclock in relation to PWM, in accordance with the invention.

DETAILED DESCRIPTION OF THE INVENTION

The aim of this invention is to cover LED (but not limited to thattechnology) display devices which are optimized for studio/onscreen/camera applications (i.e. studio having a (LED-)screen (e.g. inthe back, behind actors or presenters or stage) and using a camera forrecording scenes) whereby the picture performance needs to be changed oradapted in order also to have acceptable performance on camera and tohave acoustic performance so that when put in cube (or cubical) and/ordome or circularly shaped screen (i.e. other shapes than standard cubesare also referred to) that act as a background for e.g. actors that alsohave acceptable acoustic performance so that the sound doesn't bounceoff from the screen directly and also acceptable real-time recording ofactor conversations is achieved. This is just an example of usage,but—as one can easily deduct—has also advances in e.g. home theatres orcinemas where this display system is used. As mentioned, LED displaydevices are given by means of example, and are mostly referred to inthis description, although the invention is not limited thereto. Hence,display devices or displays in general based on either light-emitting aswell as light-reflecting technology are considered with the invention.

In other words, a display such as a LED display is proposed, beingadapted to studio applications, such that better conditions eitheracoustically or regarding audio, or either visually are perceived by theactors and/or players in the studio, as well as by the recording orproduction crew for a studio application. Hence, an improved performancein the making of pictures, movies, television shows or other kind ofbroadcasting, including also real-time application, in video as in audioaspects is achieved.

The technical implementation for the above described aim or proposal, isnow described into detail. A list of technical parameters that needadaptation compared to traditional displays with regard to camerarecording in an environment with (background) screen, is now given.

1. Frame Rate Latency

In case of action on the ‘background’ and in relation to foregroundaction or triggers, it is needed that the background action (on screenof the display) is totally synchronized with the audio and actorperformance in front of the screen. Traditionally this was compensatedfor by having the background play out a few frames earlier compared tothe front action, to compensate for the frame delay of the video displaysystem as schematically illustrated in FIG. 1. However, a solution thatavoids this is to reduce frame delay in the source towards on screendisplay as much as possible. Dependent on the display and datadistribution design, this can be limited to 1.5 frames or even less.This however means that the video digital pipeline and processing needsto be changed accordingly to accommodate for less frame delay, i.e. forexample using more parallel processing (implying that a strongerprocessor is needed), less buffering and avoiding timing congestionconstraints are taken into account such that that images or video datawon't appear onto the screen display in multiple bits and pieces, butpresents smoothly. It is noted that, in case of not live or notreal-time applications (but recorded, and viewed later) the audio issometimes co-delayed because of synchronization issues otherwise. Thisis of course only possible in case of recordings, that are edited orviewed later and not real-time.

2. Vertical Sync Update

Linked to the above feature, what is deemed very useful is that thedisplay can show the video (refresh the video) related to vertical syncupdate, but that the update time is programmable compared to the fixedposition of the sync signal. This means that whenever sync comes, thedisplay waits certain amount of programmed ‘clock’ before updating thescreen. This feature is very useful for determining and finding optimalexposure timings on the camera to make sure the ‘grabbing’ and or A/Dconversion (transfer signal or content to digital value) in the cameratakes place when the PWM driven screen is started, and hence lightemitting elements of the display (or e.g. LEDs of the LED display) willlight up.

On one hand, the camera has a particular so-called shutter-time(comparable with diaphragm on a lens). On the other hand, the images orvideo data is scanned vertically onto the screen or display, meaningthat the images appear in vertical sequence. The camera shutter-time maybe defined such that only part or a ribbon (e.g. between the dashedlines) of the entire screen is viewed on camera. In case this part orribbon coincides with not yet received new images entering from top tobottom of the screen, then nothing shall be seen within this part orribbon. According to an embodiment of the invention as shown in FIG. 2,there are always provided new images or video data within the ribbon,representing the shutter-time of the camera. In other words, asynchronization is provided by means of having a programmable updatetime of new entering images or the sync signal with which new images arescanned. The programable aspect implies that it can be programmed suchthat certain amount of time is waited until images are viewed orrepresented.

Going a step further, this can be done not only per screen, but alsoe.g. on tile by tile basis, or even segment by segment in case segmentsin tiles would be needed.

3. Reduce or Eliminate Banding Effects Caused by Multiplexing

Traditional displays are optimized for cost of light emitting sources orelements and electronics to drive them. By means of example, considerfor instance a LED display (as traditional display) being optimized forcost of LEDs and electronics to drive them. Hence, there is a tendency(to reduce silicon cost) to increase multiplexing ratio. Herewith isalso referred to Belgian patent application BE2019/5196 filed withpriority date 7 Mar. 2019 regarding “Real-time deformable andtransparent display” wherein multiplexing issues are described intodetail, and in particular wherein is described to reduce, avoid oreliminate multiplexing by means of using a local LED driver. Since thehuman eye does ‘slow’ integration, one has the impression that all themultiplexed LEDs are on all the time although they are time multiplexedon/off. . . . This principle in combination with the camera shutter-timecreates the typical banding effects seen on camera. Hence, in order toreduce this effect to a minimal is to reduce multiplexing as much aspossible and even have no multiplexing at all. . . . This doesn'tnecessarily mean that cost is higher because when multiplexing isreduced, the efficiency becomes higher and even cheaper LEDs can be usedas the average LED on time will be equivalently longer. Going evenfurther on this route enables us to e.g. make use of LEDs withintegrated drivers, for which again is referred to the Belgian patentapplication BE2019/5196 as mentioned above. The latter aspect ofintegrated drivers totally avoids multiplexing and hence limits, avoidsor excludes banding effects.

It is noted that we can also use the LEDs used for the deformabledisplay as described in BE2019/5196, in order not to have all theseissues on camera but for sake of this invention description we can alsolink immediately to this formerly filed Belgian patent application.

4. Set Current for Individual Colours Instead of Tuning PWM for RequiredLight Output

Another item that is typically overlooked in the light emitting elements(e.g. LEDs) or display industry is the current (I) settings to theindividual light emitting elements (e.g. LEDs). In traditional setups,these currents are fixed and light output is modulated with PWM. Butsince for studio applications, the typical needed light output is lowerthan average usage (because of e.g. background aspect of the screen instudio), if one reduces the brightness, that means that the PWM cycle isreduced and when the PWM cycle is reduced, this means the actual ‘on’time of the light emitting element or e.g. LED is less and this thenmeans that the chance of the camera shutter-time not noticing the ‘on’time of the light emitting element or e.g. LED is higher. Hence, thegrey scale reproduction on camera is not deemed ok. Therefor it isadvised to set the currents adequate (instead of tuning PWM) for eachindividual colour, as shown in FIG. 3. In other words, the current isadapted for maximum PWM per colour for achieving the required lightoutput. As a result, there is no longer loss of bits being related tocolour depth, and hence no loss of colour depth is perceived.

Moreover, the idea is to have the current of the light emitting elementsor e.g. LEDs being programmable (see also PQ curve profiling at the endof the document regarding dynamic range) to the desired maximal lightoutput at the desired colour temperature (for colour temperature seelater in paragraph 9. as there can be also camera profiling involved . .. referral to the principle of metamerism).

5. RLC Behaviour and Non-Linear Effects

The importance of previous current setting is now further motivatedbecause of the RLC behaviour of PCB board (electronics). Constantcurrent drivers with PWM function typically are deemed linear. This isin general the case. However, in the lowlights (i.e. the region wherenot a lot of light is needed, very small grey scale detail) this is notthe case. The main reason for this is due to routing layout on PCB boardand hence the traces and routing lines have a typical RLC behaviour. Forhigh resolution displays (<3 mm or higher resolution, linked withmultiplexing lines routed on the PCB, especially the RC has a negative(or destroying) effect on the grey scale linearity. In some other caseseven, this can cause crosstalk (cfr. typical LED ghosting effects).Avoiding this issue has been described in many papers or documents andis out of the scope of this invention description. But nevertheless thatis known in the art how to avoid, the prior-art doesn't solvenon-linearities. Since also the response of the human eye is not linearto light or brightness perception, typical gamma functions need to beapplied. However, traditional systems don't take these non-linearitiesinto account. While referring to FIG. 4, to compensate for thesenon-linearities e.g. spline functions can be used to alter the lowlightdrive so that for human eye, the desired light output is achieved. Inother words, spline functions or more general non-discontinuousinterpolation is used to compensate for non-linear effects or so-callednon-linearities. See also graphical representation of FIG. 5illustrating gamma correction with e.g. spline function.

It can go even further that the function or characteristic is evendifferent for every light emitting element (e.g. LED) and/or region onthe display board (e.g. LED display board). Hence, a gamma function perpixel or region is implemented to adjust and correct for even better ormore uniform video performance.

6. Temperature Compensation

Typically, also, (O)LED/LCD boards need to have uniform temperature. Asit is known in the industry, (O)LEDs are temperature sensitive(especially and typically red dies). A combination of temperaturesensors in the (O)LED tile, together with active measurement of ‘on’time of the (O)LED (e.g. digital counters), one can estimate the red diebrightness behaviour. A circuitry to measure and compensate individuallyis added so that red brightness of the individual (O)LEDs or regions of(O)LEDs is compensated for and colour or colour temperature ismaintained. Here, the compensation is preferable on PWM and not adaptingcurrent, whereas per individual (O)LED this compensation tuning PWM ismore convenient due to cost efficient (O)LED display architecture(although in theory compensating by means of adapting current would alsobe feasible).

7. Acoustics

For typical studio applications, not only the video or colourperformance is of utmost importance, but also the acoustic behaviour ofthe display.

Regarding acoustics we have in such (studio) application 2 items tosolve:

a/ Acoustic noise of the screen itself. This can be either due the useof fans or even psu (power supply) noise (typical coil vibrations.) Thelatter has to be solved by means of better design to reduce this noise(frequency, potting, phasing of current draw). The first one can bereduced by making the fan speed dependent on cooling required and eventurn off when threshold is deemed ok for safe operation. Also, thethermal design of the display or e.g. LED tile can help a lot. It isnoted that internal convection in closed cabinet and fan will normallyresult into less audible noise compared to an open design.

b/ Studio noise due to the geometry of state-of-the-art displays instudio applications. This is the most important for studio applications:since the typical screens are flat or plane, being curved they form avery sizeable surface that reflects sound or noise, which is not deemedto be a good characteristic (e.g. screen behind camera shoot whereactors have a conversation reflects the conversation such that the echoand noise makes the conversation inaudible for the actors themselves).Multiple solutions are proposed:

Open screen (being characterized by a certain degree of (acoustical)transparency, and for which referral can be made to the open structureof the deformable display as described in patent applicationBE2019/5196) of which example is shown in FIG. 6 (a)

Open screen with (sound absorbing) cloth behind of which example isshown in FIG. 6 (b)

Screen with Optical Enhancer on Top

Acoustic absorbing and/or diffusing material in between light emittingelements or e.g. LEDs

Acoustic absorbing and/or diffusing surface in between light emittingelements or e.g. LEDs

Acoustic absorbing and/or diffusing surface (e.g. made black) in betweenlight emitting elements or e.g. LEDs and transparent on top of the lightemitting elements or e.g. LEDs

For the acoustic absorbing material and/or surfaces (in between thelight emitting elements or e.g. LEDs) is referred to the illustrationsof FIGS. 7 to 9. The optical enhancer as referred to above, may alsohave the function e.g. to change the beam angle of the light sources(e.g. LEDs) or to add diffuseness and increase e.g. perception of fillfactor. Moreover, the optical enhancer may at the same time be anacoustic enhancer under the condition that the structure or architectureis conform the acoustic wavelength. FIG. 10 shows an example of astandard screen and its sound reflections in comparison with an acousticenhanced screen, in accordance with the invention.

A few embodiments, in accordance with the invention, of a studio settingwith enhanced visual and/or acoustic performance are described withFIGS. 11-13. FIG. 11 shows an embodiment of a studio setting, wherein acamera is surveying a display wall making noise, in accordance with theinvention. The display wall or e.g. LED-wall has to perform well toachieve good captured images with the camera. Adaptation of settings inthe display wall are made such that a correct representation of imagesis achieved after having been captured by the camera.

FIG. 12 shows an embodiment of a studio setting, wherein a camera issurveying an actor and a display wall of which the noise is suppressedor reduced by means of for example fan regulation or light outputadaptation, in accordance with the invention. The noise or sound beingemitted by the display wall is typically fan noise, of the fan presentthere within for cooling purposes. By means of either excluding orremoving the fan, or else regulating or modulating it with the generatedheat, the noise can be reduced or suppressed. The fan is for exampleforced for operating or turning slower and hence making less noise, whenthe temperature has become lower. Alternatively, when reducing the lightoutput of the display wall, less power is involved and thus less heatwill be generated by the display wall. As a result, the fans present canautomatically be slowed down or maybe even turned in some occasions.

FIG. 13 shows an embodiment of a studio setting, wherein a camera issurveying actors talking and a display wall of which the noise issuppressed or reduced as FIG. 12, and wherein the display wall isprovided with acoustic absorbing or diffusing material, or the displaywall having an open structure, such that audio wave reflections from thesurface of the display wall are suppressed or reduced, in accordancewith the invention. The display wall, more in particular for instanceits wall surface facing the studio environment and/or the actors, canalso reflect sound or audio waves. Particularly when the display wall iscurved, the effect on e.g. the actors will be even stronger. As asolution for eliminating such audio reflections from the display wall,an open structure or architecture for the display can be opted. Anotherpossible solution is providing for example an acoustic absorbing and/ordiffusing material in (e.g. between the LEDs) or onto (e.g. as a surfacelayer) the display wall.

8. Add markers as well. Referral can be made here to markers asdescribed in the Belgian patent application BE2019/5196. Screen markerscan be either embedded in the acoustic absorbing and/or diffusingmaterial or can be generated by the light emitting elements or e.g.LEDs. These markers can be used for e.g. geometric reference settings ofthe image recorded by the camera. Alternatively, the markers can also beused as a reference to map and geometrically alter the display contentso that it matches the desired on-screen positioning. Further on, suchmarkers might also be used for interactive scene playing whereby theycan be used for cameras embedded in head up displays to create immersiveenvironments.

9. Colour Conversion at the Display (e.g. LED Display) and Hence ColourConversion in Camera is No Longer Necessary.

As illustrated in FIG. 14, the light emitted colour spectrum for Red,Green, Blue of the display is not necessarily the same as the cameracolour sensitivity curves, although part of the spectra can beoverlapping. Hence, the camera will perceive the colours differentlycompared those exposed by the display.

A traditional solution for this flawed colour capture by the camera isthat operators tune the RGB (or other) colour gains in the camerasetting itself. But this has a detrimental effect, because the perceivedcolours seen though the camera will look acceptable when recording thedisplay, but the colour representation (as seen through the camera) fromthe background, person(s), actor(s), performer(s) or presenter will alsochange. Hence, using this traditional adjustment always requires a‘good’ enough approach meaning that this (manual) adjustment will alwaysresult in ‘OK enough’ or just perceived adequate on camera for both thedisplay as well as the environment. In other words, it will never beperfect for both.

Therefore, a more appropriate solution is proposed by means of adaptingthe screen side or the LED-display or LED-wall itself. For example, hereat the display side, individual colour intensities can be changed, suchthat these will be recorded as needed by the camera. Since only thedisplay (primary) colours intensities are changed, this will have noeffect on the ‘environment’ or scene. Therefore, the camera recordingwill look perfect for scene and display. Since the colour sensitivity ofprofessional and semi-professional cameras is well documented and known,one can add for example a display setting indicating which type ofcamera is used so that no manual intervention is needed anymore. Themethod for deriving the cored setting will be based on the knowledge ofthe primary colours of the displays and inputting the camerasensitivity. This method can be even used for mobile phone cameras.

But still, as a result, the visual perception for the human eye might beheavily disturbed now (since the colour perception of the human eye isdifferent from that of a camera). Therefore, extra colours can be added(e.g. cyan, orange) to the display or e.g. LED-wall, such that thedisturbance is eliminated, and the human eye visual perception iscorrected and hence satisfactory. Adding extra colours to the displaymeans in fact adding multiple colour spectral elements. The multiplespectral elements will enable display being capable of making use of thecolour theory called ‘metamerism’ whereby it is perfectly possible toshow the same perceived colour using completely different spectralsettings.

In fact, this ‘challenge’ is part of a broader aspect of display andlight sources for photography and video applications. This display in astudio environment is also acting as a light source whether this isdesired or not. As indicated earlier, the light spectrum of typical LEDillumination devices, such as typical red-green-blue (RGB) LED devices,is fixed and does not match to the light spectrum of, for example,natural sunlight or of industry-standard white light sources, such ashalogen lamps, tungsten lamps, and fluorescent lamps. Therefore, whenusing LED illumination devices, the resulting reflected light may notmatch that of natural sunlight or industry-standard light sources.Consequently, the reflected imagery that results from the LEDillumination devices may not appear correctly as perceived by the humaneye or as captured by a still camera or video camera (e.g. standard filmor digital image capture), as compared with the reflected imagery thatresults from natural sunlight or standard light sources. While it may bepossible to apply manual filtering in combination with the LEDillumination, manual filtering is not adequate to provide matching forall colours.

For these reasons, alternative approaches are needed for enabling thewidespread use of LED illumination in, for example, photography andvideo applications. Therefore, a need exists for a system for and methodof matching the spectrum of a multi-colour LED illumination device tothe spectrum of any white light source.

FIGS. 15A and 15B illustrate a schematic overview of a spectral analysissystem for matching the spectrum of a multi-spectral display (withmulti-colour LEDs) to the spectrum of any white light source whilst alsotaking into account the camera sensitivities. FIG. 16 is the accordingflow diagram.

FIG. 16 illustrates a functional block diagram of a spectra analysissystem 100 for matching the spectrum of a multi-colour LED illuminationdevice to the spectrum of any white light source, in accordance with theinvention. Spectra analysis system 100 includes a reference light source110 that may be any commercially available white light source, such as,but not limited to, one or more commercially available halogen lamps,tungsten lamps, fluorescent lamps, hydrargyrum medium-arc iodide (HMI)lamps, and any combinations thereof. For example, reference light source110 may be a Kino Flo 3200 fluorescent lamp from Kino Flo Inc. (Burbank,Calif.) or a Lowell 3200 tungsten lamp from Lowel-Light Manufacturing,Inc. (Brooklyn, N.Y.); where 3200 refers to a lamp colour temperature(CT) of 3200 Kelvin (K). Additionally, reference light source 110 may berepresentative of natural sunlight.

Additionally, spectra analysis system 100 includes a multi-colour LEDlight source 114 that is, for example, an LED white light source that isformed of at least the combination of RGB plus one additional colour,i.e. a 4-colour LED light source. Preferably, multi-colour LED lightsource 114 is an LED white light source that is formed of thecombination of RGB plus three additional colours, i.e. a 6-colour LEDlight source. In one example, multi-colour LED light source 114 is a6-colour modular LED lighting device More specifically, the colours thatform the 6-colour modular LED lighting device may include, but are notlimited to, red, green, white, cyan, orange, and blue.

Spectra analysis system 100 further includes a reference colour pallet118, which is the reference colour pallet of colours to be illuminatedby reference light source 110 and multi-colour LED light source 114.Reference colour pallet 118 may be any user-determined number of coloursby which the light spectrum of reference light source 110 andmulti-colour LED light source 114 may be analysed. In one example,reference colour pallet 118 may be a Munsell or Macbeth colour chartthat may include, for example, about 8 to about 24 colours.

Spectra analysis system 100 further includes a reflectance spectrometer122. Reflectance spectrophotometers measure the amount of lightreflected by a surface as a function of wavelength to produce areflectance spectrum. For a target sample that is illuminated by white,the operation of a spectrophotometer is to calculate the amount of lightthat is reflected at each wavelength interval. Referring to FIG. 16,reflectance spectrometer 122 is used to calculate the light that isreflected from reference colour pallet 118 when it is illuminated byreference light source 110 or by multi-colour LED light source 114.Reflectance spectrometer 122 may be any commercially availablespectrometer.

Spectra analysis system 100 further includes a set of one or more imagecapture devices 126. Image capture devices 126 may include, for example,but are not limited to, a video camera 130, a movie camera 132, adigital camera 134, and a film camera 136. Video camera 130 may be anycommercially available video camera for recording moving imageselectronically, such as those used in the television industry. Moviecamera 132 may be any commercially available movie camera for recordingmoving images on film, such as those used in the motion pictureindustry. Digital camera 134 may be any commercially available digitalcamera for recording still images digitally, such as those availablefrom Sony Corp. (Tokyo, Japan), Canon Inc. (Tokyo, Japan), and EastmanKodak Company (Rochester, N.Y.). Film camera 136 may be any commerciallyavailable film camera for recording still images on film, such as 35 mmcameras from Olympus Imaging America Inc. (Melville, N.Y.), Canon Inc.(Tokyo, Japan), and Eastman Kodak Company (Rochester, N.Y.).

Spectra analysis system 100 further includes a computer 150 that may beany commercially available handheld, laptop, desktop, or networkedcomputing device. Residing on computer 150 is a system controller 154that may be any commercially available controller, microcontroller, ordigital signal processor (DSP) device that is capable of executingprogram instructions, such as those of an LED light source controller158 and a spectra analysis algorithm 162. Furthermore, system controller154 manages the overall operations of spectra analysis system 100,including managing the communications and data transfer between hardwareand software components thereof.

LED light source controller 158 may be a software or hardware controllerthat is associated with multi-colour LED light source 114. LED lightsource controller 158 provides the interface between spectra analysisalgorithm 162 and multi-colour LED light source 114. In particular, LEDlight source controller 158 reads in a set of associated multi-colourLED settings 166, which are operating parameters that are then passed onto multi-colour LED light source 114, thereby setting the light outputthereof. Example operating parameters for multi-colour LED light source114 may include, but are not limited, to colour temperature, overalldevice power level, individual intensity level of each of the multiplecolours.

Spectra analysis algorithm 162 may be a software algorithm that executesprogram instructions that are required for matching the spectrum of amulti-colour LED illumination device, such as multi-colour LED lightsource 114, to the spectrum of any white light source, such as referencelight source 110. A source of input data to spectra analysis algorithm162 may be, but is not limited to, device specification data 170, imagedata 172, and reflectance data 174. In one example, device specificationdata 170 may include certain specification information, such as theoptical filter specifications and response curve information, of eachimage capture device 126 of interest (e.g. video camera 130, moviecamera 132, digital camera 134, and film camera 136) and of the humaneye. This information may be supplied by the manufacturer of each imagecapture device 126. In another example, device specification data 170may include certain specification information for reference light source110, such as the spectra information that may be supplied by themanufacturer of a certain light source device. If not supplied by themanufacturer, the spectra information of reference light source 110 maybe measured via reflectance spectrometer 122 and stored in devicespecification data 170. In the case of image capture devices 126 thatare digital, image data 172 may be the digital image data that isreturned therefrom. Reflectance data 174 may be the data that isreturned from reflectance spectrometer 122 that includes the amount oflight that is reflected from reference colour pallet 118 at eachwavelength interval.

The operations that are performed by control of spectra analysisalgorithm 162 may include, but are not limited to, the following:

activating/deactivating the reference light source, either automaticallyvia system controller 154 or, alternatively, by prompting a user via auser interface (not shown) to manually activate/deactivate the referencelight source;

activating/deactivating the multi-colour LED light source, eitherautomatically via system controller 154 and LED light source controller158 or, alternatively, by prompting a user to manuallyactivate/deactivate the multi-colour LED light source;

activating/deactivating the reflectance spectrometer, eitherautomatically via system controller 154 or, alternatively, by promptinga user to manually activate/deactivate the reflectance spectrometer;

storing the data that is returned from the reflectance spectrometer;

calculating and storing the difference between the reflectance of thereference light source and the reflectance of the multi-colour LED lightsource;

determining and storing the optimal output settings of the multi-colourLED light source for matching the spectrum of the reference lightsource;

applying any optical filter characteristics of interest to the optimaloutput settings of the multi-colour LED light source;

using the optimal output settings of the multi-colour LED light source,initiating an image capture event via one or more image capture devices,either automatically via system controller 154 or, alternatively, byprompting a user to manually perform the image capture operation; and

reading in the image data from the one or more image capture devices andverifying that the spectrum of the multi-colour LED illumination devicesubstantially matches the spectrum of the reference light source.

10. Since traditional (surface mount) LEDs have a particular RGB diearrangement within a package, the colours emitted in all directions willbe slightly different. Hence, one can turn these LEDs 90°/180° degreesin alternating ways to overcome these viewing angle issues, but can alsohave the acoustic shader take care of it. A diffuser lens may be mountedon top of the LEDs, or light emitting elements in general of the displayused, not only for uniformity aspects, but providing simultaneously astructure for dampening acoustically (or sound absorption and/ordiffusing). With such optical diffuser lens, a rather closed design isproposed, although a more open design would also be an improvement, e.g.particularly acoustically wherein the open grid added material comprisesonly sound absorbing and/or diffusing characteristics, and is providedas a matrix in between the LEDs of the display. In an embodiment, theoptical diffuser (e.g. lens) for enhancing/changing the display'soptical characteristic, may as well act as acoustic diffuser.

11. Dynamic Range

Since LED screens have the potential to have a very high dynamic range(i.e. Brightness of 5000 nits and more), there is a need to show thefull dynamic range defined by e.g. PQ gamma curve as defined in BT2100.

https://www.eizoglobal.com/library/management/ins-and-outs-of-hdr/index2.html

also available in FIG. 17 of the drawings set.

The range is between 0 and 10.000 nit as this gamma definition is basedupon absolute brightness.

The range to show all the incoming values distinctly requires at least24 bits when using PWM. Most common LED constant current PWM drivershowever are limited to 14 bit (and in some exceptional cases to 16 bit).

So, in order to show this full dynamic range without grey scale loss,this is not possible. However, what is proposed are several solutions tothis issue for achieving a wider than standard dynamic range:

dependent on desired clustered content, adjust also the current of thePWM driver. Increasing the current will also increase the LEDs lightoutput. This is in most cases not linear, but since we can characterizethis behaviour, this can be compensated for using a formula, dependenton required brightness. In the ideal case there is a current setting foreach individual LED, but not al PWM LED drivers in the field have thisfunction. Generally, one particular PWM driver current setting is commonfor a group of LEDs, and thus all LEDs (e.g. 8 or 16) hooked up to thePWM driver in particular will be affected. In case that each LED has acurrent setting, then the cluster is of course one LED. An algorithmcould e.g. be: determine max nit level for LEDs in particular clusterdependent on content, and set current for this particular LED or LEDs tomax LED current. Dependent on this current, determine other values ofLEDs and use PWM to set to desired brightness using spline curveadaptation.

in combination with or independent form the above, there is also analternative way to generate a gamma like behaviour. In all existingsystem today, people are working with a fixed frequency clock togenerate a PWM cycle. E.g. in case of 12 bit, to achieve 50% ofbrightness, one sets PWM high for 2048 counts out of the 4096. This isschematically shown in FIG. 18 (a). Alternatively, as illustrated inFIG. 18 (b), one can modulate the clock, i.e. higher frequency at thestart of the PWM cycle to a lower frequency at end of PWM cycle. This infact means that the ‘lowest’ bit on time is shorter (and this is exactlywhat is needed in a gamma curve). So, stand alone or a combination of agamma look up table and modulation of the grey scale clock in frequencyduring PWM cycle can mathematically give you more than 24 bit of ‘grey’scales if one sees it in a linear frequency time domain. And this isexactly what we want, and considered very important while not at allknown from the art.

However, in some circumstances, showing the full dynamic range is notreally desired (e.g. when the screen is used to see or evaluate how thepicture or movie looks like on a traditional display (e.g. monitor orprojector) that cannot achieve the full dynamic range of the 10.000nit). One can use e.g. the spline curve adaptation to set the maximalbrightness to the monitor brightness (and/or also change the globalcurrent to the LEDs for the desired colour and brightness) and then showthe content in the REAL—fixed brightness (and even the same colourpoints=>see calibration as for example described in patent applicationBE2019/5196 regarding a deformable display) as if it was shown on thatmonitor and or projector.

1. A method for improving the interplay of a light source display with acamera recording the image displayed by the light source display, themethod comprising: (i) receiving the light source input signal; and (ii)applying the light source input signal to said light source, after aprogrammable delay relative to a synchronisation signal related to saidcamera.
 2. The method of claim 1, wherein said light source being aLight Emitting Diode (LED).
 3. The method of claim 1, wherein saidprogrammable delay being selected to improve said interplay of saidlight source display with said camera, to reduce banding effects.
 4. Amethod for improving a light source display visual performance for alight source display, comprising a plurality of distinct light sources,mounted on a (PCB) board, the method comprising: for at least one lightsource, (i) receive the light source input signal; (ii)) adapt the lightsource input signal, to compensate for nonlinearities, caused by the(RLC) behaviour of said board; and (iii) apply the adapted light sourceinput signal to said light source.
 5. A method for determiningadaptation information (correction factors) suited for use in the methodof claim 4, the method comprising: (a) displaying an image or sequenceof images (video) with said light source display; (b) determine thevisual performance perceived by a human eye after camera recording theimage displayed by the light source display; (c) compare this visualperformance with the ideal visual performance; (d) compute saidadaptation information (correction factors) based on said comparison. 6.A method for using light-emitting or light-reflecting light sourcedisplays being part of a studio environment, with one or more of saiddisplays, one or more cameras at least in part surveying what isdisplayed on one or more of said displays, wherein at least one of saiddisplays comprises an arrangement for visual enhancement of said atleast one display, and/or wherein said studio environment comprises atleast one arrangement for acoustic adaptation.
 7. The method of claim 6,wherein said displays are adapted to minimize their sound generatingbehaviour, and/or said displays are adapted to maintain good visualperformance irrespective to an improved sound generating behaviour. 8.The method of claim 6, wherein said displays are adapted to optimizeacoustic behaviour of the studio, in particular either said displays areprovided with acoustic absorbing and/or diffusing material and/oradapted to let part of the sounds through.